Answer:
The correct answer is immune and circulatory system.
Step-by-step explanation:
The immune system is formed of the thymus, bone marrow, spleen, and lymph nodes. The circulatory system comprises the heart, the lungs, and the blood/blood vessels. The immune system relies upon the circulatory system in order to remain healthy. The body requires WBCs to defend against the diseases that would not be able to flow via the body in the absence of the circulatory system fulfilling its activity.
Maintaining a balance within the body is very crucial in remaining healthy known as homeostasis. The immune system maintains homeostasis by eradicating any foreign substances. On the other hand, the circulatory system maintains homeostasis by spontaneously supplying the blood and essential components like WBCs from the immune system to the entire body.